Question about a Windows XP Pro based network

I was wondering if any of you people would be able to help me out, i have about 20 computers on a small network where each person logs onto the computer with their username and password, and they all have windows xp pro, and they're all hooked up to 1 hp laser printer. i want to know how to limit the number of pages that each user prints say to 20 pages, or if i can't stop it at least have it tell me the administrator. i want to do this without having to buy $500 software, i would imagine that it's possible through network settings or applying a security policy but i just can't find a way, any help would be much appreciated.